Calculate the pH of a 00100 M solution of potassium azide KN

Calculate the pH of a 0.0100 M solution of potassium azide, KN3. pH =

Solution

Ka of HN3 = 2.5×10^–5

pKa = -log Ka = -log (2.5×10^–5)

        = 4.60

this is a salt of strong base and weak acid. so pH > 7

pH = 7 + 1/2 (pKa + log C)

     = 7 + 1/2 (4.60 + log 0.0100)

pH = 8.30